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Re: No Programs Listed in "Media Library" [ In reply to ]
On Mon, Jan 27, 2014 at 2:00 PM, Michael T. Dean <mtdean@thirdcontact.com>wrote:

> In that case, and because of the "RemoteGetRecordingList() list size
> appears to be incorrect." message, I'd guess that there was some
> corrupt/unhandled data in your channel data that, when channel information
> was pulled in for display with your recordings, caused a failure. I'm not
> sure what exactly could cause that, but I'd (wild) guess it could be
> something like a null character in a channel name or call sign or something
> like that. If so, it would be good to find out exactly what was causing it
> so that we could write code to prevent such bad data getting into the
> database.
>

I think you've nailed it. I noticed in the list of channels that a local
broadcaster has several channels whose names ended with an garbled
character rendered on the screen kind of like "3ABN Teaching Tâ–¡" (rather
than "3ABN Teaching TV"). I didn't watch or knowingly record those
channels, and in fact, I deleted them from the list this time around. But I
do have a copy of the backend.log I ran with the debug setting:

http://pastebin.com/JB4nTtK7

And I observe that the log line corresponding to a normal channel looks
like this:

2014-01-22 20:54:24.766968 D MSqlQuery::next(DBManager1) Result: "channum
= 16_1, callsign = KDTL-DT, chanid = 1161, atsc_major_chan = 16,
atsc_minor_chan = 1, name = KDTL-DT, icon = , mplexid = 7, visible = 1,
sourceid = 1, GROUP_CONCAT(DISTINCT cardinput.cardid) = 4,2,3,1,
GROUP_CONCAT(DISTINCT channelgroup.grpid) = , xmltvid = 77034"

while one for one of the offending channels is missing everything after the
weird character, like this:

2014-01-22 20:54:24.767209 D MSqlQuery::next(DBManager1) Result: "channum
= 25_3, callsign = 3ABN-DD, chanid = 1253, atsc_major_chan = 25,
atsc_minor_chan = 3, name = 3ABN Teaching T

And looking at a database backup I made when I was having the problem, I
can see that the character in the channels table is \0
Re: No Programs Listed in "Media Library" [ In reply to ]
On 01/27/2014 04:52 PM, Tom Wheeler wrote:
> On Mon, Jan 27, 2014 at 2:00 PM, Michael T. Dean wrote:
>
>> In that case, and because of the "RemoteGetRecordingList() list size
>> appears to be incorrect." message, I'd guess that there was some
>> corrupt/unhandled data in your channel data that, when channel information
>> was pulled in for display with your recordings, caused a failure. I'm not
>> sure what exactly could cause that, but I'd (wild) guess it could be
>> something like a null character in a channel name or call sign or something
>> like that. If so, it would be good to find out exactly what was causing it
>> so that we could write code to prevent such bad data getting into the
>> database.
>>
> I think you've nailed it. I noticed in the list of channels that a local
> broadcaster has several channels whose names ended with an garbled
> character rendered on the screen kind of like "3ABN Teaching Tâ–¡" (rather
> than "3ABN Teaching TV"). I didn't watch or knowingly record those
> channels, and in fact, I deleted them from the list this time around. But I
> do have a copy of the backend.log I ran with the debug setting:
>
> http://pastebin.com/JB4nTtK7
>
> And I observe that the log line corresponding to a normal channel looks
> like this:
>
> 2014-01-22 20:54:24.766968 D MSqlQuery::next(DBManager1) Result: "channum
> = 16_1, callsign = KDTL-DT, chanid = 1161, atsc_major_chan = 16,
> atsc_minor_chan = 1, name = KDTL-DT, icon = , mplexid = 7, visible = 1,
> sourceid = 1, GROUP_CONCAT(DISTINCT cardinput.cardid) = 4,2,3,1,
> GROUP_CONCAT(DISTINCT channelgroup.grpid) = , xmltvid = 77034"
>
> while one for one of the offending channels is missing everything after the
> weird character, like this:
>
> 2014-01-22 20:54:24.767209 D MSqlQuery::next(DBManager1) Result: "channum
> = 25_3, callsign = 3ABN-DD, chanid = 1253, atsc_major_chan = 25,
> atsc_minor_chan = 3, name = 3ABN Teaching T
>
> And looking at a database backup I made when I was having the problem, I
> can see that the character in the channels table is \0

Wow, lucky guess on my part. Thanks a lot for looking into it and
confirming. We'll have to get a patch in to scrub the names the channel
scanner is putting in the database, and potentially any data being sent
over the protocol.

Who would have thought that broadcasters have started to null-byte
attack their users. ;) Then again, maybe this is a rebroadcaster/cable
company--in which case I wouldn't be surprised to find out it actually
/was/ intended as a null-byte attack against users(-owned equipment).

I may remove the addition to the FAQ entry just because it's unlikely to
be a common case--and I'm hoping we'll have MythTV patched to handle it
soon. (Where "we" is likely one of the other devs, who have actually
been getting work done on MythTV.)

Thanks, again.

Mike
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